Phytoplasmas diversity and identification of new aster yellows subgroup (16SrI) associated with weed species in Argentina

Symptoms of phytoplasma infection were observed in different weed species, Bidens subalternans, Conyza bonariensis, Heterosperma ovatifolium and Conium maculatum, collected from diverse geographical regions in Argentina. To confirm the association of phytoplasma infection with symptomatic plants, PCR, RFLP and phylogenetic analyses based on 16S rRNA-encoding sequences were performed. In this work, we report the presence of phytoplasmas from group 16SrVII (subgroup 16VII-B) infecting C. bonariensis and B. subalternans and from group 16SrIII (subgroup 16SrIII-X) B. subalternans, H. ovatifolium, and C. maculatum. Phytoplasmas from the aster yellows group were detected infecting C. bonariensis and B. subalternans. Analysis of 16S rRNA-encoding genes revealed the presence of two distinct operons, rrnB (16SrI-B) and newly described rrnA, which is different from the reference RFLP patterns of all previously established 16SrI-subgroups. A single rp operon sequence analysis reveals the presence of simple infection and confirms a description of a novel subgroup. On the basis of these results we propose a designation of new subgroup 16SrI-(B/AJ) AJ (rp-AJ). To our knowledge, this is the first report of phytoplasmas infecting Bidens subalternans¸ Heterosperma ovatifolium and Conium maculatum.Fil: Fernandez, Franco Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Galdeano, Ernestina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Conci, Luis Rogelio. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentin

Detection of genotypes with multiple disease resistance in argentinean maize germplasm

Maize (Zea mays L.) is usually affected by multiple co-occurring pathogens. Therefore, selection of multiple disease resistance (MDR) is becoming a necessary area of research. In this study, we aimed to reveal genotypes with MDR in the Argentine public inbred maize collection and to determine the best selection strategy for their identification. We evaluated 87 Argentinean inbred lines for their response to four foliar diseases: common rust (CR), northern corn leaf blight (NCLB), southern corn leaf blight (SCLB) and bacterial leaf streak (BLS) in up to five environments of Argentina. All diseases were evaluated using a 1-5 scale, where 1=highly resistant and 5=highly susceptible. Phenotypic data was analyzed using mixed models to obtain the BLUP (best linear unbiased predictors) of genotypes. We assayed four strategies for multi-trait selection: MDR variable, Elston index, principal component analysis (PCA), and Factor analysis and ideotype-design. Then, we compared them based on their efficiency and genetic gain. Our results showed that the panel of genotypes was plenty of genotypes resistant to CR and BLS, while resistant genotypes to NCLB and SCLB were scarce. We obtained significant genotypic variation and high heritability (H2>0.82) for all disease resistances, indicating that selection can be performed with a high efficiency for all of them. We found twelve genotypes resistant to all diseases in the panel of genotypes. The PCA showed the highest efficiency for selecting those genotypes (92%) and presented an average genetic gain of 19%. Our findings will benefit breeders for strengthening broad-spectrum resistance in temperate breeding programs, as well for the study of MDR.Fil: Kistner, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; ArgentinaFil: Nazar, L.. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Centro de Bioinvestigaciones (Sede Pergamino); ArgentinaFil: Montenegro, L.. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Centro de Bioinvestigaciones (Sede Pergamino); ArgentinaFil: Cervigni, Gerardo Domingo Lucio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Galdeano, Ernestina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Iglesias, J.. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Centro de Bioinvestigaciones (Sede Pergamino); Argentina5to Congreso Argentino de Fitopatología; 59th Meeting of the APS Caribbean DivisionCorrientesArgentinaAsociación Argentina de FitopatólogosAmerican Phytopathological Societ

Occurrence of corn stunt diseases and maize viruses in the Provinces of Tucumán and Córdoba in Argentina

A incidência de doenças causadas por molicutes e por vírus foi avaliada em lavouras de milho (Zea mays) nas Províncias de Tucumán e de Córdoba, na Argentina, em fevereiro de 2000. Na Província de Tucumán verificou-se que 44% das lavouras apresentaram altos níveis de incidência de plantas com sintomas de enfezamentos causados por molicutes (50 a 100%), em altitudes variando de 300 a 2.000 m. A presença de fitoplasma e de espiroplasma foi confirmada em amostras de folhas de plantas com sintomas de enfezamentos, através dos testes de PCR e de "Western blotting". Constatou-se, porém, que a eficiência desses testes para detecção destes patógenos, quando os sintomas apresentados pelas plantas eram muito acentuados, foi da ordem de 70%, e de apenas 30% quando os sintomas eram menos acentuados. Na localidade Jesus Maria, foram encontradas plantas apresentando acentuado nanismo, folhas estreitas e com deformações. Dentre quatro amostras destas plantas, submetidas a testes de PCR, em duas foi detectada a presença de fitoplasma, possivelmente d istinto do "Maize Bushy Stunt Phytoplasma". A cigarrinha Dalbulus maidis, inseto vetor dos molicutes, foi encontrada apenas em Tucumán, estando ausente em Córdoba. O Mal de Rio Cuarto virus foi detectado em seis lavouras em Córdoba, e em três em Tucumán. A cigarrinha Delphacodes kuscheli foi detectada em todas as lavouras em Córdoba, e em apenas três lavouras em Tucumán. O Maize dwarf mosaic virus foi detectado em cerca de 60% das lavouras amostradas nas duas Províncias e o Maize rayado fino virus em apenas uma localidade em Tucumán.The incidence of "corn stunt diseases" and maize (Zea mays) viruses was evaluated in maize fields located at the Provinces of Tucumán and Córdoba in Argentina in February 2000. A high number of plants infected with "corn stunt disease" were observed in Tucumán (up 50 to 100%) in 44% of maize crops surveyed in areas varying from up 300 to 2000 m high. The presence of Maize Bushy Stunt Phytoplasma (MBSP) and Corn Stunt Spiroplasma (CSS) was confirmed by PCR and Western blotting tests. In plants showing typical symptoms of MBSP or CSS, the pathogens were detected in 70% of the samples. However, when symptoms were weak, the efficiency of detection dropped to approximately 30%. In Rio Cuarto, Province of Córdoba, the presence of phytoplasma was detected only in three plants showing red leaf symptoms. In Jesus Maria locality, plants showing symptoms different from those caused by MBSP, were demonstrated to be infected by phytoplasma when analyzed by PCR using universal primers. The leafhopper Dalbulus maidis, vector of MBSP and CSS, was found only in Tucumán. The Mal de Rio Cuarto virus (MRCV) was found in six maize fields in Córdoba and in three maize fields located at 1970 to 2.000 m high in Tucumán. The plant hopper Delphacodes kuscheli, vector of MRCV, was found in both provinces sampled. The Maize dwarf mosaic virus (MDMV) was found in 60% of maize crops in both Provinces and the Maize rayado fino virus (MRFV)was found only in one location in Tucumán

Genetic diversity of 16SrIII group phytoplasmas in Argentina. Predominance of subgroups 16SrIII-J and B and two new subgroups 16SrIII-W and X

Twelve Argentinean 16SrIII (X-disease)-group phytoplasma strains were analyzed. Ten of them, detected in daisy (Bellis perennis), garlic (Allium sativum), ‘lagaña de perro’ (Caesalpinia gilliesii), periwinkle (Catharanthus roseus), ‘rama negra’ (Conyza bonariensis), ‘romerillo’ (Heterothalamus alienus), summer squash (Cucurbita maxima var. zapallito) and tomato (Solanum lycopersicum), are new phytoplasma strains while two strains, detected in garlic and China tree (Melia azedarach), have been previously described. The plants showed typical symptoms of phytoplasma diseases, such as leaf size reduction, proliferation, stunting and virescence. The identification and genetic diversity analysis of the phytoplasmas were performed based on 16S rDNA and ribosomal protein gene sequences. The classification into 16Sr groups and subgroups was established by actual and virtual RFLP analysis of the PCR products (R16F2/R16R2) compared with reference strains. According to the classification scheme, strains HetLL and ConWB-A and B represent two new subgroups 16SrIII-W and X, respectively. On the other hand, strains CatLL, TomLL and CaesLL are related to subgroup 16SrIII-B, and strains BellVir, TomRed, CucVir and GDIII-207 are related to subgroup 16SrIII-J. Ribosomal protein genes were amplified using primers rpF1/rpR1 and rpIIIF1/rpIIIR1. RFLP analysis performed with AluI, DraI and Tru1I (MseI isoschizomer) distinguished three new rp profiles within subgroup 16SrIII-B, one for subgroup 16SrIII-J, and one shared with strains of the new subgroups 16SrIII-W and X. The phylogenetic analysis based on 16S rDNA and ribosomal protein gene sequences confirmed the separation of HetLL and ConWB strains in two new subgroups and the close relatedness among subgroup J phytoplasmas, which have been detected only in South America.Instituto de Patología VegetalFil: Galdeano, Ernestina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Nordeste. Instituto de Botanica del Nordeste; Argentina;Fil: Guzman, Fabiana. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patología Vegetal; ArgentinaFil: Fernandez, Franco Daniel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patología Vegetal; ArgentinaFil: Conci, Luis Rogelio. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patología Vegetal; Argentin

Sphenospora kevorkianii on the orchids Epidendrum paniculatum and Stanhopea graveolens newly reported in Argentina

Plants of Epidendrum paniculatum and Stanhopea graveolens were collected in May 2007 as part of a native orchids preservation project in Baritú National Park, a protected area of the Yungas subtropical forest located in the province of Salta (Northwestern Argentina). The causal agent of the rust diseases was identified as Sphenospora kevorkianii. Urediniospores were ovoid yellowish and echinulate. The telia observed on E. paniculatum were subepidermal and erumpent, in which numerous clavate paraphyses were found besides the pedicelated teliospores, longitudinally one-septate, hyaline and thin walled. This is the first report of Sphenospora kevorkianii infecting E. paniculatum and S. graveolens in Argentina.Fil: Cúndom, M. A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Galdeano, Ernestina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Tarrago, Jose Ramon. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Flachsland, Eduardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentin

Description of 'Candidatus Phytoplasma meliae', a phytoplasma associated with Chinaberry (Melia azedarach L.) yellowing in South America

China tree yellows (ChTY) phytoplasma is associated with the yellowing disease of the China tree (Melia azedarach) in Argentina. According to partial 16S rRNA gene analysis, ChTY phytoplasma belongs to the 16Sr XIII group, subgroup G. Strains of species of ChTY have 98–99 % 16S rDNA gene sequence similarity with 16SrXIII-group phytoplasmas, and less than 97.5 % when compared to all ‘Candidatus Phytoplasma ’ described so far, except for the novel ‘Candidatus Phytoplasma hispanicum '. However, strains of species of ChTY are differentiated from the latter due to having additional molecular and biological attributes. The presence of unique features in the 16S rDNA sequence distinguishes ChTY from all species of ‘Candidatus Phytoplasma ’ currently described. The in silico RFLP profile of 16S rDNA (1.2 kb) and rpLV-rpsC (1.3 kb) genes distinguished ChTY, as in the 16SrXIII-G subgroup within the 16SrXIIII group. The phylogenetic analyses, based on 16S rDNA, rpLV-rpsC and secA gene sequences, in addition to the restricted host range, characteristic symptoms and geographical distribution, confirm that the collective strains of the species ChTY represent a distinct lineage within the phytoplasma clade and support the description of a novel species of ‘Candidatus Phytoplasma meliae ’ with the reference strain being ChTY-Mo3 (Montecarlo, Argentina).Fil: Fernandez, Franco Daniel. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Galdeano, Ernestina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Kornowvsky, Marcela Victoria. Instituto Nacional de Tecnología Agropecuaria; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Misiones. Estación Experimental Agropecuaria Montecarlo; ArgentinaFil: Arneodo, Joel Damián. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Microbiología y Zoología Agrícola; ArgentinaFil: Conci, Luis Rogelio. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentin

Diversity of endophytic fungal and bacterial communities in Ilex paraguariensis grown under field conditions

The composition and diversity of the endophytic community associated with aerial organs of yerba mate (Ilex paraguariensis) was investigated using culture-depending methods. Fungal and bacterial endophytes were isolated from young and adult leaves and branches of three yerba mate clones growing under field condition in Corrientes province, Argentina. Fungi were identified based on their micromorphological characteristics and internal transcribed spacer (ITS) rDNA sequence analysis; for bacteria 16S rDNA sequence analysis was used. A total of 156 fungal and 193 bacterial isolates were obtained. Bacteria predominated in stem samples while leaf samples retrieved similar amount of bacterial and fungal isolates. No significant differences were found in isolate quantity nor diversity among seasons or between young and older leaves and stems. The most frequently isolated fungus was Fusarium, followed by Colletotrichum; they were both present in all the sampling seasons and organ types assayed. Other 12 fungus genera were identified including Aspergillus, Cercospora, Clonostachys (Bionectria), Curvularia, Guignardia, Microsphaeropsis, Neofusicoccum, Nigrospora, Paecilomyces, Penicillium, Phomopsis (Diaporthe), and Phyllosticta. Actinobacteria represented 61% of all bacterial isolates. The most dominant bacterial taxa were Curtobacterium and Microbacterium. They were isolated from all the organs assayed, showing that they are ubiquitous endophytes. Other bacteria frequently found throughout the year were Methylobacterium, Sphingomonas, Herbiconiux and Bacillus. The predominant fungi and bacteria detected in yerba mate were similar to those reported in other species in which the same type of technique was used.Fil: Pérez, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Collavino, Mónica Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Sansberro, Pedro Alfonso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Mroginski, Luis Amado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Galdeano, Ernestina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentin

Caracterización molecular de un fitoplasma del grupo ash yellows (16Sr VII-B) presente en las malezas Artemisia annua y Conyza bonariensis

En Sudamérica se han detectado y caracterizado fitoplasmas de diferentes grupos 16Sr. Entre éstos, se detectaron fitoplasmas del grupo 16Sr VII (ash yellows) infec- tando diferentes especies de plantas herbáceas. En Brasil, se reportaron los aislamientos EriWB y RPWB infectando Erigeron sp. y Catharanthus roseus, los que fueron asignados al nuevo subgrupo 16Sr VII-B. En la Argentina, el subgrupo 16Sr VII-C fue creado para incluir al fitoplasma ArAWB que infecta alfalfa (Medicago sativa). Nuevos aislamientos de fitoplasmas del grupo 16Sr VII se han detectado en Artemisia annua y Conyza bonariensis en la Argentina, mostrando típicos síntomas de "escoba de bruja". El objetivo de este trabajo fue caracterizar molecularmente a estos aislamientos para clasificarlos y asociarlos a los fitoplasmas más relacionados. Se analizaron patrones de restricción (PCR-RFLP) del gen 16S de ARNr y se obtuvieron secuencias de tres aislamientos para realizar un análisis cladístico y poder determinar la similitud con otros fitoplasmas. Idénticos patrones de PCR-RFLP, la alta similitud de secuencias (99,9%) y el agrupamiento cladístico resultante asociaron a estos fitoplasmas presentes en malezas en Argentina (ArtWB), al subgrupo 16Sr VII-B. Estos aislamientos representan aislamientos geográficos del fitoplasma EriWB. Este trabajo revela la amplia distribución geográfica de los fitoplasmas del subgrupo 16Sr VII-B y su capacidad de infectar diferentes hospedantesIn South America, plants infecting phytoplasmas from different 16Sr groups have been detected and characterized. Among them, 16Sr VII (ash yellows) phytoplasmas have been detected in herbaceous plants. In Brazil, EriWB and RPWB isolates infecting Erigeron sp. and Catharanthus roseus have been assigned to a new 16Sr VII-B subgroup. In Argentina, 16Sr VII subgroup C was created to enclose the ArAWB phytoplasma which infects alfalfa (Medicago sativa) plants. Recently, new isolates from the 16Sr VII group phytoplasmas have been detected in Artemisia annua and Conyza bonariensis showing typical witches' broom symptoms. The aim of this work was to perform a molecular characterization of these isolates in order to classify them and associate them to their closest relatives. A restriction analysis on PCR fragments (PCR-RFLP) from the 16S rRNA gene was performed. Sequences of three isolates were obtained to perform a cladistic analysis and to reveal their similarity to other phytoplasmas. Identical PCR-RFLP patterns, high sequence similarity (99.9%) and the cladistic grouping associated the new phytoplasma isolates infecting weeds in Argentina with the 16Sr VII-B subgroup. ArtWB strains represent geographic isolates of the EriWB phytoplasma. This work reveals the wide distribution of 16Sr VII-B phytoplasmas and their capability to infect different host plants.Fil: Meneguzzi, Natalia. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucuman-Santiago del Estero. Estación Experimental Agropecuaria Famaillá; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Torres, Laura. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Galdeano, Ernestina. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Guzmán, F. A.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Nome, Sergio Fernando. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Conci, Luis Rogelio. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentin

Detecting sources of resistance to multiple diseases in Argentine maize (Zea mays L.) germplasm

Maize (Zea mays L.), an important cereal for human and animal nutrition, is usually affected by multiple co-occurring pathogens that reduce production. Argentina is the fourth maize producer worldwide, with common rust (CR), northern corn leaf blight (NCLB), southern corn leaf blight (SCLB) and bacterial leaf streak (BLS) being important yield-limiting diseases in most maize producing areas. In this study, we aimed to identify genotypes with multiple disease resistance (MDR) for the introgression of broad-sense resistance into temperate maize breeding programs. We evaluated 87 genotypes from the Argentine public temperate inbred maize collection available from Instituto Nacional de Tecnología Agropecuaria (INTA) for their response to CR, NCLB, SCLB and BLS in up to five environments of Argentina. We compared four strategies to select sources of resistance to multiple diseases that could be used in breeding programs. Significant genotypic variation and high heritabilities were found for all disease resistances. The panel of inbred lines had numerous genotypes resistant to CR (80%) and BLS (78%), whereas genotypes resistant to NCLB (26%) or SCLB (30%) were less frequent. However, we were able to identify 12 genotypes as potential candidates for the introgression of broad-sense resistance. Our results indicate that the selection based on principal component analysis (PCA) was the most accurate methodology to detect MDR across all accessions. Maize studies based on MDR are scarce; to our knowledge, this is the first study conducted on Argentine germplasm. These findings will contribute to the strengthening of broad-sense resistance in temperate breeding programs as well as to the study of MDR detection.EEA PergaminoFil: Kistner, María Belén. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Departamento de Maíz; ArgentinaFil: Kistner, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nazar, Lázaro. Universidad Nacional del Noroeste de la Provincia de Buenos Aires; ArgentinaFil: Montenegro, Lucía Daniela. Universidad Nacional del Noroeste de la Provincia de Buenos Aires; ArgentinaFil: Cervigni, Gerardo Domingo Lucio. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cervigni, Gerardo Domingo Lucio. Universidad Nacional de Rosario. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Galdeano, Ernestina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Galdeano, Ernestina. Instituto de Botánica de Noroeste (IBONE); ArgentinaFil: Iglesias, Juliana. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Departamento de Maíz; ArgentinaFil: Iglesias, Juliana. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Escuela de Agrarias, Naturales y Ambientales; Argentin

Epidemiological aspects of garlic decline disease caused by a phytoplasma in Asiatic and Argentinean garlic cultivars

Garlic decline is a disease that has been detected in most of the garlic-growing areas of Argentina. The associated pathogen has been identified as a 16SrIII-group phytoplasma. Little is known, however, about epidemiological aspects of the disease. Incidence and prevalence of the disease were analysed during 3 consecutive years infields of an Asiatic garlic cultivar (Chino) and two Argentinean cultivars (Blanco and Colorado) from the principal garlic-growing areas of Argentina. Although low incidence was registered (0.03–0.78%), disease prevalence was high in both sampled regions (23–100% fields had at least one diseased plant). Cultivars Chino and Blanco were more susceptible to the disease since incidence and prevalence were significantly higher than in cv. Colorado. The pathogen was detected by polymerase chain reaction (PCR) in a high proportion of cloves from infected plants and in plants derived from potentially infected cloves, showing that the phytoplasma can be transmitted from a crop cycle to the following by planting infected cloves. The phytoplasma was detected by transmission electronic microscopy,PCRand dot blot immunoassay in all parts of the symptomatic plants, and the highest pathogen concentration was found in root tissues. Although 22 leafhopper species were found associated with the garlic crop, insect populations were low during the whole crop cycle.Fil: Galdeano, Ernestina. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Conci, Luis Rogelio. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: González, Orlando. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Mendoza - San Juan. Estación Experimental Agropecuaria San Juan; ArgentinaFil: Paradell, Susana Liria. Universidad Nacional de La Plata. Facultad de Cs.Naturales y Museo. Area Zoologia; ArgentinaFil: Di Rienzo, Julio Alejandro. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Departamento de Desarrollo Rural. Area de Estadística y Biometría; ArgentinaFil: Nome, Claudia. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Conci, Luis Rogelio. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin